Opt Lasers 6X Cylindrical Testing

[RedCowboy]

Accutronitis that is an idea I have had too, that and adjusting the primary/G2 on the fly.

I think I may try the same thing. :beer:

Is your black cap 3D printed?

-----EDIT----

I don't know if I told you, but I have much better results with my 3X BE after the 6X pair if I use a sanwu G2, the sawnu G2 seems to have a slightly different focal length.

 

[paul1598419]

Donno either, but it appears to expand both axis, does it not? One more than the other though. Strange to do that, I think... my best guess, that's all. Robinson wrote back to me and said on Tuesday he will be testing those lenses and get back with me with some more info.

Yes, that is what it appears to do. I just don't see the advantage of this. I look forward to any news on these you make come by. :thanks:

 

[RedCowboy]

I can use a G2 and 6X pair on a NUBM44 and at 75 feet the line thickness is more than a NDB7875 through a 3 element even though the line width is greatly improved, I can see the use in keeping the line thickness sharper, more energy in a smaller area.

 

[paul1598419]

Yes, that would be an advantage, if it works to actually do that. Need to see some results before I'll believe it is actually increasing the energy density of the beam.

 

[Accutronitis]

Being able to move the last lens let's me "fine tune" the beam for more intensity over a larger difference of local lengths, It really dose help.....

 

[RedCowboy]

Yes I have played with the tight spot distance, I am glad you are able to keep the lens in 3 dimensional alignment and be able to slide it, the beam expander however gives a very good result after the 6X as well.

I set some paper lunch bags at 50 feet last week and the 06 GBall with 3X BE could not light it, the 44 with 3 element and 3X BE tried like hell and smoked holes but could not reach flash point, but the 44 with G2 and 6X plus the 3X BE lit it up in seconds, so far it gives the best result.

It is fun to set a 6X pair for short range such as 6 - 12 feet, that makes a mean burner, but to really reach out it needs the BE as well.

 

[Alaskan]

RCB, those results are so cool, using a beam expander seems counter intuitive in regard to a more intense power density due to making the beam wider, but with combined correction and expansion you have less overall divergence to produce a more intense spot, nice work bro! Happy to see your results I would't have thought correction would add more burning power at distance.

 

[Accutronitis]

Yep, To be able to reach out farther then the 6X I added the Opt 3X lens for a 18X expansion which doesn't really look any wider then it did with the 12X Opt 3X plus the Lsp 4X combo expansion......

Yes I have played with the tight spot distance, I am glad you are able to keep the lens in 3 dimensional alignment and be able to slide it, the beam expander however gives a very good result after the 6X as well.

I set some paper lunch bags at 50 feet last week and the 06 GBall with 3X BE could not light it, the 44 with 3 element and 3X BE tried like hell and smoked holes but could not reach flash point, but the 44 with G2 and 6X plus the 3X BE lit it up in seconds, so far it gives the best result.

It is fun to set a 6X pair for short range such as 6 - 12 feet, that makes a mean burner, but to really reach out it needs the BE as well.

 

[RedCowboy]

@ Alaskan, yes it's more work but correcting the rapidly diverging axis...well reducing it a lot then using an adjustable beam expander gets the power into a small point at further distance and at the medium range ( 20 feet ) it is amazing how fast it burns.

I have tested all the other common ways and this gets the hottest spot the furthest, for cutting up close a G2 is fine and for a bit of 20 foot burning fun I have been using the better focused GBall 06 diodes with the 3X BE, another easy way to go is the 44 with 3 element and 3X BE, but correcting the divergence before adding a BE is the right 1st step for the best variable range results, even at mid range the spot is tighter and a fast burner, I really want to buy or build wider expanders to use after correction with these multi mode diodes and with possibly future GBalls we will want bigger beam expanders, they do work so long as the optics can accommodate the beam width/divergence in combination with the magnification factor.

 

[Accutronitis]

Just some observations now that I've had some time to work with the sets of cylindrical lenses for the fast axis correction.

I have seen many people use cylindrical lenses for the fast axis correction but I don't recall any of them talk about focal length of the fast axis after correction AND there definitely is a focal length after correction, How long that focal length is depends on the distance between cylindrical lenses. every NUBM44 build I've seen use cylindrical lenses for the fast axis correction the cylindrical lenses were fixed and in most cases the lenses were not easily moved later on.

The focal length that produces the narrowest fast axis at 1 foot away requires the cylindrical lenses to be farther apart from each other, Now move that focal point out to 15 away and that will require the cylindrical lenses to be much closer together in order to produces the narrowest fast axis.

So what I'm saying is if you want your fast axis beam to be as narrow as is possible over varying distances when using cylindrical lenses you need to make to make the last cylindrical lenses focusable (movable) or you will only have the narrowest beam profile possible on the fast axis at just one focal length, any closer in OR out and the focal point will be out of focus and it won't be the narrowest it could be.....

 

[paul1598419]

I have wondered how this contraption of yours manages to keep the lenses aligned as to pan, tilt and height. It would make more sense to me if the two rulers you have the cylindrical pair on were actually held in contact with each other. This might help to keep the lenses aligned properly.

 

[RedCowboy]

You are still only acting on 1 axis, the cylindrical pair as you know is a beam expander that works on just 1 axis.

Your adjusting the convex cylindrical lens will work in the short range in this case but you can not get a burning spot at 100 feet with it, you need to correct the aggressive axis for the best compromise rectangle then use a round lens beam expander to manipulate the entire corrected beam.

Remember these are not single mode diodes with round/square beams where each axis diverges at the same rate, we are working with a compound problem.

Your solution is short range as once you adjust your convex cylindrical past your best far field focus your corrected axis gets wider again, this is only useful in the short 30-40 foot distance for this diode and even if you used a 24X cyl pair you would start very wide on the aggressive axis but end up outrunning the slower diverging axis until it was wider in the far field, it's a better compromise to correct the aggressive axis for divergence then use a round lens beam expander which will work in the short range as well.

If you are happy burning in the short range then your compromise will help this diode to do that no doubt, but so will a round lensed beam expander after correction plus you will get more range that you can use as well.

 

[paul1598419]

^^This^^^
Is also a good point. If you are trying to get the best energy density out in the far field, the use of an adjustable BE is going to work much better,.

 

[Accutronitis]

The cyl lenes pair is correcting the highly divergent fast axis only, Using only a G-2 lens and without the cyl lenes pair and the beam shot up in the night sky more closely resembles a very thin and wide hand fan shape. no matter how you focus the G-2.....

Using a G-2 lens With the cyl lenes pair and the beam shot up in the night sky the beam can be easily adjusted to be a thin on both axis's/small square beam that is tight and parallel, OR with my adjusting convex cylindrical lens it can also burn at 20 feet like it's nobody's business !

Or you can feed that small parallel beam into a beam expander with no clipping going into the beam expander for burning at a distance..........


The original point I was making was if you correct a 44's fast axis with a cyl lens pair and fix the convex cylindrical lens for the best beam focused to infinity it will not be a very good up close burner or not the best it could be unless you move the convex cylindrical lens OR if you fix the convex cylindrical lens for the smallest dot up close for insane burning it will have a lousy looking beam shot up into the night sky....

You can't have both with a "fixed" convex cylindrical lens was my point......



AND YET SPEAKING OF THE SLOW AXIS ONLY once you adjust the G-2 lens for the thinnest and tightest (densest) slow axis it doesn't matter if you check the slow axis at 1 foot or 500 feet that setting will always be the tightest (densest) you will be ever able to get the slow axis, Which is really pretty dang tight using a DTR G-2 lens !
Of couse adding a cyl lens pair to the fast axis should have no effect on the slow axis other than the losses from the slow axis having to go through two more lenses for no reason, But that is the best case with the cyl lens pair adjusted for correct alignment,

Except in the case you add a beam expander which will make the slow axis tighter at large distances BUT again if the beam expander is added after convex cylindrical lens for fast axis correction the beam expander output lens will act just like the fast axis convex cylindrical lens did before you fix it for use with the beam expander and if you adjust the beam expander for the best beam focused to infinity for the best looking beam shot up into the night sky it will not be a very good up close burner or not the best it could be unless you readjust the beam expander OR if you adjust the beam expander for the smallest dot up close for insane burning it will have a lousy looking beam shot up into the night sky unless you readjust the beam expander just like with convex cylindrical lens before the use of a beam expander...

 

[RedCowboy]

What you see at a distance and what the spot is really doing can be very different.

Your method has usefulness in the short range, even if used pre expander, just as tuning the G2 pre Cyl correction can help in the short range, but it is limited to short range.

The test is on a real target at 100 feet, the cyl pair has limitations as any optical train, adding an expander will extend your ability to focus smaller further and your cyl pair will be set to infinity when it's at it's best far field.

Short range your method has use.

 

[Accutronitis]

Your method has usefulness in the short range, even if used pre expander, just as tuning the G2 pre Cyl correction can help in the short range, but it is limited to short range.

That's not what I've experienced when using nothing but the DTR G-2 lens, By that I mean if I adjust the G-2 lens for the tightest profile focused to infinity that setting will be the best setting even much closer until you get within a foot or two, only then can you start to be able to adjust the G-2 for a slightly better dot.

I guess what I'm also trying to say is even with fast axis cyl lens pair correction the two axis's still act differently from each other a lot of the time ?